39989921 has 4 divisors (see below), whose sum is σ = 40169472. Its totient is φ = 39810372.

The previous prime is 39989897. The next prime is 39989993. The reversal of 39989921 is 12998993.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12998993 = 7 ⋅1856999.

It is a cyclic number.

It is not a de Polignac number, because 39989921 - 2⁶ = 39989857 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 39989921.

It is not an unprimeable number, because it can be changed into a prime (39983921) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 89441 + ... + 89886.

It is an arithmetic number, because the mean of its divisors is an integer number (10042368).

Almost surely, 2^39989921 is an apocalyptic number.

It is an amenable number.

39989921 is a deficient number, since it is larger than the sum of its proper divisors (179551).

39989921 is a wasteful number, since it uses less digits than its factorization.

39989921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 179550.

The product of its digits is 314928, while the sum is 50.

The square root of 39989921 is about 6323.7584552227. The cubic root of 39989921 is about 341.9664621764.

It can be divided in two parts, 3998992 and 1, that added together give a palindrome (3998993).

The spelling of 39989921 in words is "thirty-nine million, nine hundred eighty-nine thousand, nine hundred twenty-one".